Allow automated labelling of partitions

lib/modules/partition.nix

@@ -88,6 +88,7 @@
                     format
                     index
                     keepExisting
+                    label
                     sizeScript
                     type
                   ;
@@ -102,6 +103,12 @@
                     ${fs.fat32} = "mkfs.fat -F 32 ${diskVar}";
                   };
 
+                  labelScripts = {
+                    ${fs.ext4} = label: "e2label ${diskVar} ${label}";
+                    ${fs.ntfs} = label: "ntfslabel ${diskVar} ${label}";
+                    ${fs.fat32} = label: "fatlabel ${diskVar} ${label}";
+                  };
+
                   create = lib.strings.concatLines [
                     (appendScript "${toString index}: \"$(${sizeOption})\" type=${lib.strings.escapeShellArg type}")
                     formatScripts.${format}
@@ -115,6 +122,7 @@
                   '';
                 in [
                   (if keepExisting then fallback else create)
+                  (labelScripts.${format} label)
                 ])
               partitions)
           );